The World Health Organization (WHO) has warned that unless certain pharmaceutical companies change their practices, the malaria parasite could develop resistance to the world’s most effective drug for treating the disease.

Made from a plant used in traditional Chinese medicine, artemisinin is nearly 95 per cent effective at curing malaria.

To limit the chance of the parasites developing resistance to the drug, the WHO advises combining it with others in what are called artemisinin-based combination therapies (ACTs).

Last year, the WHO urged countries to ban the use of artemisinin unless in ACTs, and yesterday (19 January) went a step further by demanding that drug companies stop marketing and selling artemisinin on its own.

According to the Financial Times, the WHO's senior malaria official,Arata Kochi, said that if the companies refused to do this, the WHO would consider taking other measures, including urging the World Bank and the Global Fund to fight AIDS, TB and Malaria to withdraw funding.

"If we lose ACTs, we’ll no longer have a cure for malaria, and it will probably be at least ten years before a new one can be discovered," said Kochi.

"It is critical that artemisinins be used correctly," said WHO director-general Lee Jong-wook, in a press release. "We are concerned about decreased sensitivity to the drug in South-East Asia, which is the region that has traditionally been the birthplace of anti-malarial drug resistance."